Field of the Invention
The present invention relates to a substrate cleaning apparatus for cleaning a substrate, such as a wafer, and more particularly to a substrate cleaning apparatus having a cleaning vessel for cleaning a substrate. The present invention also relates to a polishing apparatus provided with such a substrate cleaning apparatus.
Description of the Related Art
A polishing apparatus, which is typified by a CMP (chemical mechanical polishing) apparatus, polishes a surface of a wafer by providing sliding contact between the wafer and a polishing pad while supplying a polishing liquid (i.e., slurry) onto the polishing pad. The polishing liquid, which contains abrasive grains therein, and polishing debris remain on the polished surface of the wafer. Thus, after polishing of the wafer, cleaning of the polished wafer is performed.
There is an apparatus for cleaning a wafer by supplying a chemical liquid onto the wafer in a cleaning vessel. This type of cleaning apparatus is configured to supply the chemical liquid, which has an etching action, onto a surface of the wafer to thereby remove foreign matters that are attached to the wafer. Recently, in order to enhance the etching action, a high-temperature chemical liquid having a temperature of around 80° C. may be used. The use of such a chemical liquid having a strong etching action makes it possible to remove the foreign matters which could not be removed by a conventional chemical liquid.
However, the use of the chemical liquid having the strong etching action may corrode the cleaning vessel of the cleaning apparatus. The corrosion of the cleaning vessel due to the chemical liquid can be prevented if a material with high corrosion resistance is used to constitute the cleaning vessel. However, such a material having high corrosion resistance is expensive, and therefore use of such a material increases costs of the cleaning apparatus as a whole.